Image forming apparatus with power transmission system configured to attenuate oscillation

Abstract

An image forming apparatus includes an image carrier that rotates by power generated by a driving source. A power transmission system transmits the power from the driving source to the image carrier. The power transmission system includes a coupling member to attenuate oscillation. The coupling member includes a viscous fluid, male and female fittings, and a rotating resistor. The viscous fluid provides a resistance against rotation of the image carrier. The male and female fittings are mutually fitted and rotatably supported on a rotary shaft of the image carrier penetrating through the male and female fittings in a direction in which they are mutually fitted. The rotating resistor is accommodated together with the viscous fluid in an accommodation space defined by a recess of the male fitting and a bottom inner surface of the female fitting. The rotating resistor integrally rotates with the rotary shaft.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. An image forming apparatus comprising:
 an image carrier configured to drivingly rotate by power generated by a driving source; and 
 a power transmission system configured to transmit the power from the driving source to the image carrier, the power transmission system comprising a coupling member serving as a damper configured to attenuate oscillation, the coupling member comprising:
 a viscous fluid configured to provide a resistance against rotation of the image carrier, 
 a male fitting having a recess formed by an inner circumferential surface of the male fitting and an inner bottom surface of the male fitting, 
 a female fitting having an inner bottom surface, 
 the male fitting and the female fitting being fitted with one another so that the inner bottom surface of the male fitting faces the inner bottom surface of the female fitting, 
 a rotary shaft of the image carrier penetrating through the male fitting and the female fitting in a direction in which the male fitting and the female fitting are fitted with one another, 
 a rotating resistor being configured to integrally rotate with the rotary shaft, 
 the male fitting and the female fitting each being rotatable relative to the rotary shaft, and 
 the rotating resistor being positioned together with the viscous fluid in the recess of the male fitting so that the rotating resistor is surrounded by the inner circumferential surface of the male fitting and so that the rotating resistor is bordered on opposite sides by the inner bottom surface of the male fitting and the inner bottom surface of the female fitting. 
 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein the coupling member has an inner peripheral portion having a sectional profile in a form of a comb, and the rotating resistor has a sectional profile in a form of a comb in mesh with the comb of the sectional profile of the inner peripheral portion of the coupling member. 
     
     
       3. An image forming apparatus comprising:
 an image forming unit configured to form a toner image on an image carrier; 
 a transfer unit configured to transfer the toner image formed on the image carrier to a recording medium; 
 a driving source configured to drivingly rotate the image carrier; and 
 a power transmission system configured to transmit power from the driving source to the image carrier, the power transmission system comprising:
 a first member rotatably coupled to the driving source and having an interior accommodation space, 
 a second member sharing a common shaft with the first member and rotatably coupled to the image carrier, 
 a spring having one end coupled to the first member and another end coupled to the second member so as to transmit rotation of the first member to the second member, and 
 at least one rotating resistor enclosed together with a viscous fluid in the interior accommodation space of the first member so that the rotating resistor is not exposed to an exterior of the first member, the rotating resistor being configured to rotate in the interior accommodation space of the first member by a driving force generated by the driving source. 
 
 
     
     
       4. The image forming apparatus according to  claim 3 ,
 wherein the interior accommodation space of the first member is coaxial with the shaft, 
 wherein the interior accommodation space of the first member has a cylindrical space, and the at least one rotating resistor comprises a cylindrical structure fitting in the cylindrical space of the accommodation space of the first member with a gap disposed between the cylindrical space and the cylindrical structure, and 
 wherein the viscous fluid is disposed between a wall of the at least one rotating resistor and a wall of the first member. 
 
     
     
       5. The image forming apparatus according to  claim 3 ,
 wherein the first member comprises a plurality of cylindrical protrusions coaxial with the shaft and positioned in the interior accommodation space of the first member, 
 wherein the at least one rotating resistor comprises a plurality of cylindrical protrusions coaxial with the shaft to fit in the plurality of cylindrical protrusions positioned in the interior accommodation space of the first member with a gap disposed between the plurality of cylindrical protrusions of the at least one rotating resistor and the plurality of cylindrical protrusions, and 
 wherein the viscous fluid is disposed between a wall of the plurality of cylindrical protrusions of the at least one rotating resistor and a wall of the plurality of cylindrical protrusions. 
 
     
     
       6. The image forming apparatus according to  claim 3 ,
 wherein the interior accommodation space of the first member has a plurality of disk-shaped spaces along the shaft, 
 wherein the at least one rotating resistor comprises a plurality of disks fitting in the plurality of respective disk-shaped spaces with a gap disposed between the plurality of disks and the plurality of respective disk-shaped spaces, and 
 wherein the viscous fluid is disposed between a wall of each of the plurality of disks and a wall of each of the plurality of respective disk-shaped spaces. 
 
     
     
       7. The image forming apparatus according to  claim 3 , wherein the spring comprises a coil spring wound coaxially with the shaft. 
     
     
       8. The image forming apparatus according to  claim 1 , wherein the male fitting is rotatably mounted on the rotary shaft by a bearing. 
     
     
       9. The image forming apparatus according to  claim 3 , wherein the first member is rotatably mounted on the common shaft by a bearing.